[PATCH v3 1/2] x86: Skip XSAVE state size reset if ISA level requires XSAVE

[Florian Weimer]

If we have to use XSAVE or XSAVEC trampolines, do not adjust the size
information they need.  Technically, it is an operator error to try to
run with -XSAVE,-XSAVEC on such builds, but this change here disables
some unnecessary code with higher ISA levels and simplifies testing.

Related to commit befe2d3c4dec8be2cdd01a47132e47bdb7020922
("x86-64: Don't use SSE resolvers for ISA level 3 or above").
---
v3: Use AVX build flag for the decision, not ISA level.

 sysdeps/x86/cpu-features.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index 27abaca8b7..6dfb112038 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -24,6 +24,7 @@
 #include <dl-cacheinfo.h>
 #include <dl-minsigstacksize.h>
 #include <dl-hwcap2.h>
+#include <gcc-macros.h>
 
 extern void TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *)
   attribute_hidden;
@@ -1159,6 +1160,9 @@ no_cpuid:
 	       TUNABLE_CALLBACK (set_prefer_map_32bit_exec));
 #endif
 
+  /* Do not add the logic to disable XSAVE/XSAVEC if this glibc build
+     requires AVX and therefore XSAVE or XSAVEC support.  */
+#ifndef GCCMACRO__AVX__
   bool disable_xsave_features = false;
 
   if (!CPU_FEATURE_USABLE_P (cpu_features, OSXSAVE))
@@ -1212,6 +1216,7 @@ no_cpuid:
 
       CPU_FEATURE_UNSET (cpu_features, FMA4);
     }
+#endif
 
 #ifdef __x86_64__
   GLRO(dl_hwcap) = HWCAP_X86_64;

base-commit: be61b9493d38032519e596f282f9695667402c8d
-- 
2.48.1